As previously mentioned in another one of my emails (https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=FSL;2f26d823.1803), I am writing an LPF script using log report of a FEAT GUI based HPF.

And I have a question, specifically related to this part of it:

...
/opt/fsl/fsl-5.0.9/fsl/bin/fslstats prefiltered_func_data -p 2 -p 98
2.000000 8407.000000 

/opt/fsl/fsl-5.0.9/fsl/bin/fslmaths prefiltered_func_data -thr 842.5 -Tmin -bin mask -odt char

/opt/fsl/fsl-5.0.9/fsl/bin/fslstats prefiltered_func_data -k mask -p 50
4573.000000
... 

Previously, I thought that the value of -thr parameter in the second command is actually 98th percentile value (as calculated in the previous command) divided by 10, but that turned out to be the case in only a few of the images.

So my question is, is this division by 10 a good enough estimate for this threshold or there is another way to calculate this value? if there is another way, can you please tell me how to do it?